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2 Sheets- Shee't 1. J. H. PALMER.

ELECTRIC MOTOR.

L e d 0 M v 0 N.

No. 467,048: Patented Jan. 12, 1892.

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J. H. PALMER.

ELECTRIC MOTOR.

,048. Patented Jan. 12, 1892.

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J OI-IN II. PALMER, OF BOSTON, MASSACHUSETTS, ASSIGNOR OF ONE-HALF TORICHARD SMITH, OF SHERBROOKE, CANADA.

ELECTRIC MOTOR.

, SPECIFICATION forming part of Letters Patent No. 467,048, datedJanuary 12, 1892.

Application filed March 23, 1891. Serial No. 386,056. (NomodeL) T atwhom it may concern:

Be it known that I, JOHN H. PALMER, a subject of the Queen of GreatBritain, residing at present in Boston, in the county of Suffolk andState of Massachusetts, have invented certain new and usefulImprovements in Electric Motors; and I do hereby declare the followingto be a full, clear, and exact description of the invention, such aswill enable others skilled in the art to which it appertains to make anduse the same, reference being had to the accompanying drawings, and tofigures of reference marked thereon, which form a part of thisspecification. r 5 This invention relates to improvements in electricmotors in which the armature and field-magnets are both'free to revolvein opposite directions, it being understood that their rotations aredifferential-that is, as one increases the other decreases.

Myinvention is embodied in mechanism by which theretardation of orstopping the revolution of one part is readily accomplished by theoperator of the motor. Briefly stated, this 2 5 mechanism consists in anair or fluid compressor connected with one of the revolving parts of themotor, either the armature or field-magnets,- the action and operationof which will be more fully hereinafter described.

0 The drawings represent,in Figure 1, a plan of an electric motor of theclass above described containing my improvements. Fig. 2 is an end viewof the armature and field-magnets. Fig. 3 is a view longitudinally ofthe 5 field-magnets in side elevation. Fig. 4 is a modified form ofconstruction. Fig. 5 is a detail sectional view which showsindependently-rotating field-magnets and armature.

In Fig. 1 the air-reservoir is shown in sectional elevation.

This invention relates to that class of electric motors fully describedin an application of minenowon fileand serially numbered 361,979. Inthis invention the essential feature con- 5 sisted in the constructionof a motor in which both the armature and field-magnets not onlyrevolved oppositely,but their speed or rotary movement was reverselydifierential. In the present instance my improvements relate to theapplication of a motor of this class to an at 3, while the field-magnets4 4 (see Fig. 2)

are affixed upon the shaft 5, mounted in the bearings 6 6. A commutatoris represented at 7 and the brushes at 8 8. To connect this "motor withthe axle of a street-car, I have, shown'said axle at 9 as furnished witha gear 10, while a pinion 12 (see Fig. 1) is secured to the sleeve-shaft3 of the armature. The fieldmagnets 4 are fixed to the shaft 5, asbefore stated, while the armature 2 and its sleeve shaft 3 are looselymounted on the said shaft 5, as more clearly indicated in Fig. 5,thereby leaving the said armature and field-magnets free to revolve inopposite directions. Thus it will be seen that as the speed of the car-axle, as likewise that of the armature-shaft to which it is geared,varies or the rotations cease entirely, according to the movements ofthe car, so does the speed or rotations of thefieldmagnets,butdifferentiallyso. Hencebyvary- 8o ing the resistance orwork done by the shaft 5, carrying the field-magnets and therebycontrolling the movement of said shaft, I can easily regulate therotations of the shaft 3 and thereby the speed of the car. Thus if astrong resistance is opposed to the field-shaft and its motion retardedconversely the speed of the armature-shaft is increased, it beingunderstood that the strength of the current remains constant, orapproximately so; but if 0 this resistance is removed the speed of'thefield-magnet shaft increases, while that of the armature-shaftdecreases, owing to the resistance occasioned by the load or car, whichlatter is retarded in its movement or may be entirely stopped. In anyevent, change in speed either of the armature-shaft or fieldshafttoaccelerate or retard, one is always in motion, and hence in the bestand most eflicient condition to receive an increase in the 1 0 amount ofcurrent to be passed throught it. To create this resistance at the willof the operator of the motor, I have arranged a compressor in the shapeof a stationary cylinder 14, which contains a reciprocating plunger 15,the rod 16 from which is connected with and operated by a face-plate orwrist-pin 17, mounted upon the shaft 5 of the field-magnets. From theend of this cylinder is led a pipe 18, in which is located a vent-valve19, operated by a lever-rod 20. The latter is under the control of theoperator of the m0- tor. Cooperating with the air-compressor andconnected therewith by the pipe 18 is an air-reservoir 21, provided witha check-valve 23 and safety-valve 24.

The operation of the above parts is asfollows, assuming that the car andmotor are at rest with the air-reservoir empty: Upon admission of anenergizing-current that part of the motor without any loadin thepresentinstance the field-magnets and shaftimmediately commence torotate and soon assume their maximum rate of speed, the valve 19 beingopen, and no resistance by the compressor and its plunger is thenoffered; This movement operates the compressor conn ectedtherewith,while, the vent-valve now being closed, the air-reservoir soon attains apressure. As the latter increases the rotations of the field-shaft areretarded until the maximum normal pressure is attained equal to aresistance which corresponds with a maximum load-via, the car and itsburden for the steepest gradient. At this period the fieldmagnet isapproaching its minimum rate of movement. To start the car, thevent-valve is to be closed, and this entirely or partially, according asa sudden or easy start is desired. As resistance to the rotation of thefield-magnets is created retardation occurs, as before premised, whilemovement of the armatureshaft is commenced and increased correspondinglyto the retardation of the field-shaft. Should the vent-valve be shut atonce, the rapid movement of the compressor-pistonraises the pressure inthe compressor until it is equal to the maximum pressurein the reservoirand equals the whole load of the car. A corresponding increase in speedof the armature'shaft ensues and the car is at once put in motion.Conversely with the car at full speed the field-magnets are at lowspeed, being under the retarding eifect of the airreservoir. To checkthe car the vent-valve 19 is opened, the check-valve 23 at once closes,and the shaft 5 is free to rapidly increase its the field-magnets.

rotation, while the armature-shaft 3 is correspondingly reduced inspeed.

In Fig. 4 I have shown a modified form of construetion-that is, in lieuof having the car-axle united with the shaft 3 of the armature it may beconnected with the shaft 5 of To this end I secure the pinion 12 uponthe shaft 5 and a pulley 26 upon the shaft 3, said pulley, with a belt27,

serving to operate a counter-shaft, which causes a pairofair-compressors to reciprocate, said compressors communicating with areservoir or-reservoirs as before mentioned.

I have described this mechanism as designed for the use of air; butfluid, as glycerine or oil, may be employed to create resistance withequally good results, the only essential being that such fluid asescapes by Way of the vent-valve should be returned to the system orelse fresh liquid be suppl ed.

What I claim is-- 1. The combination, with an electric motor having itsarmature and field-magnets free to revolve in opposite directions, ofmeans for retarding or stopping the revolution of one part of saidmotor, consisting of agas or fluid compressor, operated'substantially asshown, andfor purposes set forth. 7

2. In an electric motor, the combination, with a car-axle, an armaturefreely revolving in one direction, field-magnets freely revolvingin areverse direction, and an air or fluid compressor actuated by one of themoving parts, of power-transmi tting mechanism between the other movingpart and the car-axle, and a vent-valve controlled by the operator tovary the resistance of the compressor, substantially as specified.

3. In an electric motor, a car-axle, an armature-shaft, its armature,the field -magnet shaft and the field-magnets thereupon, said armatureand field-magnets being free to revolveoppositely, but atdiHerentially-varying rates of speed, and the mechanism which connectsthe car-axle with one of the moving parts of said motor, combined Withan aircompressor connected with the other of said moving parts of themotor, the air-reservoir,

its check and safety valves, and the ventvalve, with itsoperating-lever, substantially as explained.

In testimony whereof I affix my signature in presence of two witnesses.

JOHN H. PALMER. \Vitnesses:

H. E. LODGE, FRANCIS O. STANWOOD.

